Neural bases of pedal locomotion in Aplysia will be investigated by providing information on: 1) Functional neuroanatomy of the foot: the central origins and the peripheral fields of individual pedal nerves will be determined by axonal iontophoretic filling of these nerves with CO ions; the sensory and motor field of each nerve will be determined with electro-physiological techniques; 2) Kinematics of pedal locomotion: The spatio-temporal relationships among the behavioral events in the foot of the creeping Aplysia will be analyzed with the technique of cinematography and a special event recording procedure. 3) Neural correlates of locomotion: The neural circuits involved in the detachment, extension, attachment, and retraction of the foot, the pedal waves, the suction reflex, and the coordination of these will be characterized in combined electrophysiological and behavioral experiments.